title: Functional consequences of platelet binding to T lymphocytes in inflammation.
abstract: Expression of the scavenger receptor CD36 on lymphocytes is intriguing. We observed that a minor subpopulation of lymphocytes expressed CD36 on the cell surface. We investigated the source of CD36 and also the proliferation and cytokine production of these CD36(+) CD4(+) lymphocytes. Flow cytometry analysis and immunofluorescence microscopy showed that CD36(+) platelets were responsible for CD36 detection on lymphocytes. CD36 was then used as a tool to characterize lymphocytes with bound platelets. Activation-induced proliferation was lower in CD4(+) lymphocytes with bound platelets than lymphocytes without bound platelets. IL-17 and IFN-γ production was also reduced in lymphocytes with bound platelets. We then studied the presence of CD36(+) CD4(+) lymphocytes in RA patients. We observed that the percentage of CD4(+) lymphocytes with bound platelets was higher on RA patients than in healthy donors. RA patients with higher titers of anti-CCP, RF levels, and cardiovascular risk index presented a lower percentage of CD4(+) lymphocytes with bound platelets. These patients also had higher IL-17 and IFN-γ production. These results suggest that platelet-binding modifies lymphocyte function. This binding could be a regulatory mechanism in RA that confers a less severe phenotype.
authors.affiliation: Department of Immunology, Institut Recerca, IIB-Sant Pau, Barcelona, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Zamora
authors.forename: Elisabet
authors.initials: E
authors.lastname: Cantó
authors.forename: Juan C
authors.initials: JC
authors.lastname: Nieto
authors.forename: M Angels
authors.initials: MA
authors.lastname: Ortiz
authors.forename: Cesar
authors.initials: C
authors.lastname: Diaz-Torné
authors.forename: Cesar
authors.initials: C
authors.lastname: Diaz-Lopez
authors.forename: Josep M
authors.initials: JM
authors.lastname: Llobet
authors.forename: Candido
authors.initials: C
authors.lastname: Juarez
authors.forename: Sílvia
authors.initials: S
authors.lastname: Vidal
mesh_terms: D001172:Arthritis, Rheumatoid / Q000276:immunology*; D001792:Blood Platelets / Q000502:physiology*; D017252:CD3 Complex / Q000032:analysis; D018955:CD36 Antigens / Q000032:analysis / Q000502:physiology*; D015496:CD4-Positive T-Lymphocytes / Q000502:physiology*; D016207:Cytokines / Q000096:biosynthesis; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D008213:Lymphocyte Activation; D011948:Receptors, Antigen, T-Cell / Q000502:physiology
chemical_list: D017252:CD3 Complex; D018955:CD36 Antigens; D016207:Cytokines; D011948:Receptors, Antigen, T-Cell
keywords: T cell activation; human; rheumatoid arthritis